248 FIELD AND GARDEN PRODUCTS 



greater danger of injury from keeping them covered too tightly than 

 from exposure to moderate cold. 



VENTILATION. 



Open-Air. In the care of cloth-covered frames the covers are 

 left off during bright weather and the plants subjected to open-air 

 conditions. When there is danger of cold the covers are put on at 

 night, and during unfavorable weather they are frequently left on 

 during the day. While the cloth covers conserve the heat, they at 

 the same time exclude the sunlight, and if they are kept on too great 

 a portion of the time the crops will become drawn and spindling. 

 With sash-covered frames the matter of ventilation is of prime im- 

 portance. The glass admits and holds the heat of the sun's rays, 

 and during bright weather it is necessary to open the frames quite 

 early in the morning. Ventilation is accomplished by propping up 

 one end or one side of the sash on a notched stick. The rule to be 

 followed is to ventilate on the side away from the wind, so that the 

 wind will blow over the opening and not into the bed. 



Protection of Frames. The area occupied by the frames is 

 often surrounded by a high board fence or a hedge of evergreens 

 to break the force of the wind. If a large area is devoted to frames 

 it is sometimes subdivided by numerous cross fences to break up air 

 currents and lessen the force of storms. Where no heat is applied to 

 the frames the control over temperature will not be great except 

 in the prevention of too high temperature by means of ventilation 

 during bright weather. In many instances straw and burlap mats 

 are kept ready at hand for throwing over sash-covered frames 

 to prevent loss from freezing, but this would not be practicable 

 on a large scale. Sometimes the glass is covered by shoveling 

 one-half or three-fourths of an inch of soil over it, but this involves 

 considerable labor and frequently results in the breakage of a great 

 deal of glass. It is possible to ward off frost by the use of a number of 

 orchard heaters in the frame yard. These heaters burn kerosene 

 or crude oil and give off both heat and a smudge which will prevent 

 injury from a reasonable degree of cold. 



Crops Grown in Frames. The crops most commonly grown 

 in frames are lettuce, radishes, cucumbers, garden beets, parsley, 

 eggplant, peppers, and snap beans. The crops grown in the sash- 

 covered frames do not differ materially from those grown under 

 cloth. In the spring, however, many growers devote their beds 

 almost entirely to cucumbers and eggplant instead of to lettuce and 

 radishes. To the southward the cloth covers are sufficient to protect 

 the more hardy crops throughout the winter. To the northward the 

 hardy crops may be grown under sash in midwinter, and those 

 requiring more heat are grown in the spring. 



Marketing Crops Grown in Frames. -Crops grown in frames 

 are usually superior in quality and appearance to those grown in 

 the open and should be given more care in handling and marketing. 

 The cost of production is somewhat higher than for outdoor crops, 

 and it is essential that they be put up in neat packages in order to 

 bring the highest market price. The more successful growers give 



